AIIMS 2019 Zoology Vitamins Assertion Reason Question

Option B is correct because the assertion that the daily requirement of cyanocobalamin (vitamin B₁₂) is 3 mcg is true, as this is the recommended dietary allowance for adults. The reason provided, that its deficiency causes pernicious anemia, is also true; however, it does not directly explain the assertion, as pernicious anemia is a specific condition resulting from a lack of intrinsic factor needed for vitamin B₁₂ absorption, rather than the daily requirement itself.

Option A is incorrect because, while both statements are true, the reason does not adequately explain the assertion. Option C is incorrect because both statements are true. Option D is incorrect as both the assertion and reason are factual.